<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>表单概念</title>
</head>
<body>

<form action="#" method="get">
    <label>
        <input name="username" required="required" />
    </label>
    <button>get提交</button>
</form>

<form action="#" method="post">
    <label>
        <input required="required" name="username" />
    </label>
    <button>post提交</button>
</form>

<form action="#" method="post" target="_blank">
    <label>
        <input name="username" required="required" />
    </label>
    <button>新页面提交</button>
</form>

<form action="#" target="_blank" method="post" novalidate="novalidate">
    <label>
        <input name="username" required="required">
    </label>
    <button>关闭表单验证提交</button>
</form>

<form action="#" method="get" autocomplete="off">

    <label>
        <input name="username" required="required"/>
    </label>

    <button>关闭自动完成后提交</button>
</form>

</body>
</html>